The Edison type incandescent lamps and tungsten-halogen incandescent lamps are still the primary light sources in residential and commercial lighting fixtures. These lamps generally include incandescent filaments within a predetermined and non-oxidizing atmosphere which contained in a glass envelope. The energized filaments are the sources of light. Despite their wide spread use, all incandescent lamps, including the halogen types, producing approximately 10 to 16 Lumens of light output per each Watt of consumed power and have relatively short, unpredictable service life. Only 15% of electrical energy consumed by the incandescent lamps is converted to the visible light. The rest 85% of the energy is dispersed as heat energy. The average service life of incandescent lamps is varying from 750 Hours to 3,000 hours depending on quality of the manufacturer.
The incandescent lamps are manufactured in may shapes and sizes. The most popular is the teardrop shape mounted in Edison-type base. Other shapes include “R” (Reflector) types or “PAR” (Parabolic Aluminized Reflector) types. The shapes and sizes of all these lamps are dictated by the large amount of heat energy being produced. Further, the sizes and shapes of these lamps lead to specific designs of light fixtures—to fit such lamps and meet appropriate safety standards and municipal fire codes. Also, the shapes and sizes of these incandescent lamps providing desirable optimum distribution of luminous flux.
Additionally, incandescent lamps exhibit warm color of light (approximately 2900 K) and high Color Rendering Index (CRI) (approximately 100).
Fluorescent lamps exhibiting efficiencies as high as 100 lumens per watt (Lm/W) provide attractive alternative to incandescent lighting. Service life of the fluorescent light sources is significantly longer than incandescent and reaches as much as 30,000 hours. Furthermore, approximately 85% of electrical energy consumed by the fluorescent lamps is converted to visible light. The fluorescent lamps are considered to be a cool operation lamps, with a typical bulb wall temperature of 40° C.
The conventional fluorescent lamps, however, require a long tubular envelope and together with a need for auxiliary ballasting equipment, has somewhat limited their acceptance in the market. Increased use of fluorescent illumination, with attendant savings of energy, can be achieved from the development of fluorescent lamps which are directly compatible with incandescent lamps in their shapes, sizes and distribution of light. However, when a conventional fluorescent lamp is reduced in length, the luminous efficacy is greatly reduced. The loss of efficiency in prior art, short arc fluorescent lamps, has been primary attributed to two effects: (1) the voltage drop at the lamp electrodes, and therefore power loss in the lamp remains constant as the arc length is reduced, leaving only a small portion of the lamp input power available for light production; and (2) as the arc length is reduced, the voltage drop across the discharge column is, likewise, reduced. The lamp current, therefore, must be increased to maintain the input power. The positive column efficacy decreases as a function of increasing arc current. Increased lamp current causes lower positive column efficacy and shorter lamp life primarily because of excessive phosphor excitation.
It is, therefore, highly desirable to have highly efficient fluorescent lamps electrically, mechanically, and optically compatible with incandescent or tungsten-halogen incandescent lamps. Such lamps should have relatively low arc current, relatively long arc column, and very high luminous efficacy.
The tungsten-halogen PAR reflector lamps are well known on the market. They are equipped with pressed glass reflectors and lenses. They come in many sizes and have many established application on the market like: store display lighting, down lights in hotels, motels, restaurants, theaters, residences, outdoor lighting, and indoor track lighting, and more. There are number of disadvantages of halogen PAR reflector lamps. For example, a commercially sold 90 W PAR halogen lamp has an average service life of 2500 hours, has luminous efficacy of 16 Lm/W, and emitting light in color temperature limited by tungsten melting temperature to 3000° K. It is highly desirable to have a PAR reflector lamps made with fluorescent light sources having significantly longer service life, having luminous efficacy substantially higher, and having ability to emit light in wide range of color temperatures, like: 3500° K, 4100° K, 5000° K, 6500° K.
This applicant is not aware of any prior art energy efficient PAR reflector lamp fitted with a fluorescent light source, a lens and a pressed glass reflector for directing light produced by the light source, and electronic ballasts system enclosed in a housing attached to the reflector and such PAR lamp is equipped with a base for connection to the ordinary power line and capable to provide light at particularly high degree of luminous efficacy and adapted as energy efficient direct replacements for conventional tungsten-halogen and incandescent PAR reflector lamps.